This squib presents an argument for an agreement-based model of control (Borer 1989, Landau 2000, 2004, 2006, 2008), drawn from a crosslinguistic generalization about control in passives. Specifically, I show that obligatory control by the thematic subject of a passive is sensitive to a purely syntactic restriction: it is only possible if T does not agree with an overt DP. This restriction follows from the logic of an agreement-based approach, if implicit arguments participate in Agree relations (Landau 2010, Legate 2010). This generalization subsumes and derives an old observation about control, Visser’s Generalization ( Jenkins 1972, Bresnan 1982)